Wound Dressings and Cosmetic Materials from Bacterial Nanocellulose
167
Incorporation. of. insoluble. fibrous. proteins. like. collagen. into. the. more.
porous.underside.of.growing.microbial.cellulose.pellicles.is.a.difficult.task,.
but.it.is.achievable.during.G. xylinus.stationary.cultures..Their.integration.into.
the.underside.of.these.pellicles.was.achieved.only.when.the.distance.between.
collagen.fibers.at.the.flask.bottom.and.the.air–liquid.interface.(i.e.,.the.site.of.
active.cellulose.synthesis).was.as.small.as.possible..The.freeze-dried.pellicles.
(called. collagen. BC). were. 5. mm. thick. and. displayed. antioxidant. capacity..
They.scavenged.reactive.oxygen.species.such.as.peroxynitrite.anion.(ONOO − ).
and.superoxide.anion.(O 2
− )..Furthermore,.they.reduced.the.concentration.of.
interleukin.6.and.8.in.a.time-dependent.manner,.and.bound.matrix.metalloprotease.MMP-2,.but.had.no.effect.on.the.concentration.of.MMP-13.
One.of.the.chemical.modifications.of.BNC.that.has.the.potential.to.be.used.
in.the.fabrication.of.protein-containing.wound.dressings.consists.of.its.phosphorylation,.which.proceeds.more.efficiently.than.phosphorylation.of.plant.
cellulose. (Oshima. et. al.. 2011).. Due. to. the. nanofibrillar. structure. and. large.
specific. surface. area,. the. phosphorylated. BNC. exhibited. larger. adsorption.
capacity.for.certain.enzymes.(e.g.,.lysozyme).compared.with.its.phosphorylated. plant. counterpart.. Although. phosphorylated. BNC. has. not. yet. been.
used. in. the. manufacture. of. wound. dressings,. it. seems. to. be. a. promising.
. carrier.of.enzymes.or.other.proteins,.like.collagen.
Bioresorbable BNC Wound Dressings
The.resistance.of.BNC.to.digestion.by.human.body.fluids.is.thought.to.be.a.
disadvantage. in. certain. applications,. including. wound. healing. and. tissue.
regeneration,.and,.in.particular,.in.subcutaneous.uses.(Hu.and.Catchmark.
2011)..One.of.approaches.to.production.of.bioresorbable.BNC.wound.dressings. consists. of. the. binding. of. one. or. more. cellulose. degrading. enzymes..
Before.adsorption.of.tested.commercial.enzymes.on.bacterial.cellulose.it.was.
lyophilized.to.retain.its.nanostructure..The.product.containing.immobilized.
cellulases. was. freeze-dried. again. to. ensure. its. long-term. stability. during.
the. storage.. Hydration. of. this. product. caused. activation. of. BC-embedded.
enzymes..It.occurred.in.the.contact.with.wound.exudates.and.body.fluids..
To.achieve.complete.BC.hydrolysis.to.glucose.it.was.necessary.to.immobilize.
a.cellulase.optimally.active.at.slightly.acidic.pH.and.β-glucosidase.
Another.method.of.obtaining.bioresorbable.microbial.cellulose.suitable.for.
medical.and.surgical.applications.is.based.on.its.oxidation.by.sodium.periodate.followed.by.air.drying.as.described.in.U.S..Patent.7,709,631.(Table 8.3)..
Properties. of. this. material,. such. as. mechanical. stability. and. degradation.
rate,.can.be.easily.changed.depending.on.the.desired.application.
Nanocomposite BNC Dressings
Nanocomposite. materials. reinforced. with. bacterial. cellulose. became. very.
popular.because.of.their.attractive.mechanical.properties..Some.of.them.are.
167
Incorporation. of. insoluble. fibrous. proteins. like. collagen. into. the. more.
porous.underside.of.growing.microbial.cellulose.pellicles.is.a.difficult.task,.
but.it.is.achievable.during.G. xylinus.stationary.cultures..Their.integration.into.
the.underside.of.these.pellicles.was.achieved.only.when.the.distance.between.
collagen.fibers.at.the.flask.bottom.and.the.air–liquid.interface.(i.e.,.the.site.of.
active.cellulose.synthesis).was.as.small.as.possible..The.freeze-dried.pellicles.
(called. collagen. BC). were. 5. mm. thick. and. displayed. antioxidant. capacity..
They.scavenged.reactive.oxygen.species.such.as.peroxynitrite.anion.(ONOO − ).
and.superoxide.anion.(O 2
− )..Furthermore,.they.reduced.the.concentration.of.
interleukin.6.and.8.in.a.time-dependent.manner,.and.bound.matrix.metalloprotease.MMP-2,.but.had.no.effect.on.the.concentration.of.MMP-13.
One.of.the.chemical.modifications.of.BNC.that.has.the.potential.to.be.used.
in.the.fabrication.of.protein-containing.wound.dressings.consists.of.its.phosphorylation,.which.proceeds.more.efficiently.than.phosphorylation.of.plant.
cellulose. (Oshima. et. al.. 2011).. Due. to. the. nanofibrillar. structure. and. large.
specific. surface. area,. the. phosphorylated. BNC. exhibited. larger. adsorption.
capacity.for.certain.enzymes.(e.g.,.lysozyme).compared.with.its.phosphorylated. plant. counterpart.. Although. phosphorylated. BNC. has. not. yet. been.
used. in. the. manufacture. of. wound. dressings,. it. seems. to. be. a. promising.
. carrier.of.enzymes.or.other.proteins,.like.collagen.
Bioresorbable BNC Wound Dressings
The.resistance.of.BNC.to.digestion.by.human.body.fluids.is.thought.to.be.a.
disadvantage. in. certain. applications,. including. wound. healing. and. tissue.
regeneration,.and,.in.particular,.in.subcutaneous.uses.(Hu.and.Catchmark.
2011)..One.of.approaches.to.production.of.bioresorbable.BNC.wound.dressings. consists. of. the. binding. of. one. or. more. cellulose. degrading. enzymes..
Before.adsorption.of.tested.commercial.enzymes.on.bacterial.cellulose.it.was.
lyophilized.to.retain.its.nanostructure..The.product.containing.immobilized.
cellulases. was. freeze-dried. again. to. ensure. its. long-term. stability. during.
the. storage.. Hydration. of. this. product. caused. activation. of. BC-embedded.
enzymes..It.occurred.in.the.contact.with.wound.exudates.and.body.fluids..
To.achieve.complete.BC.hydrolysis.to.glucose.it.was.necessary.to.immobilize.
a.cellulase.optimally.active.at.slightly.acidic.pH.and.β-glucosidase.
Another.method.of.obtaining.bioresorbable.microbial.cellulose.suitable.for.
medical.and.surgical.applications.is.based.on.its.oxidation.by.sodium.periodate.followed.by.air.drying.as.described.in.U.S..Patent.7,709,631.(Table 8.3)..
Properties. of. this. material,. such. as. mechanical. stability. and. degradation.
rate,.can.be.easily.changed.depending.on.the.desired.application.
Nanocomposite BNC Dressings
Nanocomposite. materials. reinforced. with. bacterial. cellulose. became. very.
popular.because.of.their.attractive.mechanical.properties..Some.of.them.are.